A battery power source device, which is used as a power source of an electric vehicle or a hybrid vehicle, is constituted as follows. A plurality of (for example, six) rechargeable batteries are connected in series to constitute a battery module. Furthermore, a plurality of (for example, thirty) battery modules are connected in series to constitute a battery pack block. In order to manage an operating state of the battery pack block, a battery ECU (Electronic Control Unit), which detects a voltage, a current, and a temperature of the battery pack block so as to detect the abnormality or to perform various controls in accordance with the results of detections, is provided. A battery power source device used for a hybrid vehicle has been known as such a battery power source device. The battery power source device is constituted to supply driving electric power to a motor for driving a vehicle to run and to be charged by electric power from a generator of the vehicle.
In the case of a large-size vehicle requiring larger electric power, it is designed to connect battery pack systems, each obtained by the combination of the battery pack block and the battery ECU, in series, in parallel or in a combination of serial and parallel. FIG. 3 shows the structure of a battery power source device, in which six battery pack blocks 31 are connected in a combination of serial and parallel so as to respond to the requirements of large electric power. A battery ECU 32 is connected to each of the battery pack blocks 31. Each of the battery pack blocks 31 which are connected in a combination of serial and parallel is connected to a positive electrode charge/discharge terminal 41 and a negative electrode charge/discharge terminal 42. An operating state of each of the battery pack blocks 31 is monitored and controlled by each of the battery ECUs 32.
Sensors (not shown) for detecting a voltage of each of the battery modules, a charge/discharge current of the battery pack block 31, one or a plurality of battery temperatures at one or a plurality of points of a representative battery module, and an ambient temperature of the battery pack block 31 are provided for the battery pack block 31. An output obtained by detection of each sensor is input to each of the battery ECUs 32. The battery ECU 32 monitors an operating state of and the occurrence of abnormality in the battery pack block 31 based on the outputs obtained by detections of the input voltage, current, and temperature. At the same time, the battery ECU 32 controls cooling means such as a blower fan provided for the battery pack block 31, based on the output obtained by the detection of the temperature. Moreover, the battery ECU 32 computes an SOC (State of Charge=Quantity of accumulated electricity with respect to a battery capacity) based on the outputs of detection of the input voltage, current, and temperature. The outputs of detections such as the SOC or the voltage are externally output as operating state data of the battery pack block 31. In the case of a hybrid vehicle, the outputs of detections are input to an ECU for controlling a vehicle so as to be employed as charge/discharge control for the battery power source device.
In the case where a plurality of battery pack systems are combined to constitute a battery power source device as described above, since a battery ECU is provided for each battery pack block, the amount of electric power consumed by the battery ECU increases. Therefore, in the case where a vehicle stops for an extended period of time, there is a problem that the amount of discharge of the battery used as a power source of the battery ECU increases.
Moreover, when a vehicle stops running to be out of operation, each battery ECU stores necessary data at that moment. Each battery ECU uses the stored necessary data to start operating when the vehicle starts running again. Therefore, it is necessary to provide a non-volatile memory for storing data. As a result, as the number of battery ECUs increases, the cost adversely increases because a non-volatile memory must be provided for each battery ECU.
An object of the present invention is to provide a battery power source device of an electric power vehicle for solving problems in the case where a plurality of battery packs are combined to constitute the battery power source device.